ABSTRACT:

OBJECTIVE: To evaluate the clinical and radiologic results of proximal femoral varus derotational
and shortening osteotomy (OVRF) (Port., doesn't match name) with the use of a locked
plate in patients with cerebral palsy, classified by the gross motor functional
classification system as class IV or V.METHODS: A retrospective study of 42 patients (61 hips) with cereFbral palsy, gross motor
functional classification system class IV or V, submitted to OVRF. The minimal follow
up
was 24 months. This study evaluated clinical (age at surgery, gender, Gross Motor
Functional Classification System class, anatomical cerebral palsy classification,
and
motor pattern), pre- and post-operative radiological (neck shaft angle, acetabular
index, Reimers migration index and time until bone healing) characteristics, as well
as
post-operative complications.RESULTS: Mean pre-operative cervicodiaphyseal angle, acetabular index, and Reimers migration
index were respectively 121.6°, 22.7°, and 65.4% in uncomplicated cases, and 154.7°,
20.4°, and 81.1% in complicated ones. All parameters were statistically significant
difference between pre- and postoperative values (p < 0.05). The
patients with postoperative complications had a greater cervicodiaphyseal angle and
Reimers migration index (p < 0.0001). There were no differences in
clinical characteristics, time of immobilization, or bone healing. Fourteen patients
had
postoperative complications (33.3%), but only six required surgical treatment.CONCLUSION: The locked plate is a safe resource, with low complication rates and reproducible
technique for OVRF in the cerebral palsy population classified as gross motor functional
classification system IV and V. Greater cervicodiaphyseal angles and Reimers migration
index are associated with greater chances of postoperative complications, as well
as
gross motor functional classification system V classification.

INTRODUCTION

Cerebral palsy (CP) is the most common cause of physical disability in children in
developed countries,1 affecting 2.0-2.5 of every 1000
live births.2 One of its most morbid orthopedic
complications is hip dislocation, whose incidence is directly proportional to disease
severity, according to the Gross Motor Function Classification System (GMFCS) functional
scale. This scale defines five groups of patients according to the overall motor impairment
and their functional performance.3 Types IV and V
present the highest incidence of hip pathologies, with dislocation rates that reach
up to
70% and 90%, respectively. Meanwhile, types I, II and III have a lower incidence of
this
problem, with respective rates of up to 5%, 17% and 50%.1,4-7 Another factor related to the risk of paralytic hip
dislocation is the inability to walk after the age of 5 years.1,7,8 Paralytic dislocation of the hip is often associated
with pain and deterioration in gait, seating, and perineal hygiene care, and consequent
worsening of quality of life.1,3,6,7,9,10

Patients classified as GMFCS IV and V present, in addition to the orthopedic problems,
clinical alterations that also affect disease prognoses, such as seizures, malnutrition,
sarcopenia, osteopenia, and low cognitive capacity.2,11,12 Of these, osteopenia may have a direct influence on
the surgical procedure that is performed in most patients: varus derotational and
shortening
osteotomy (VDSO) of the proximal portion of the femur.13,14 These surgeries are
classically made with the use of angled plates; however, aiming to improve bone fixation
under osteopenia conditions, modern implants with locking screws technology have been
developed.15-17

The recent arrival of these implants in Brazil allowed their use in the treatment
of hip
deformities in the large population of neuropathic children, as well as in children
with
non-neurological diseases. This material became available at this service in 2013
and since
then around 140 patients have undergone osteotomies of the upper third of the femur.
Of
these, approximately 100 surgeries were performed in cases of paralytic dislocation
in
patients with spastic CP classified as GMFCS IV and V. Given the absence of a Brazilian
case
series with the use of these implants, this study is aimed at demonstrating the preliminary
results of the authors' initial experience with them.

METHODS

After the project was approved by the local Research Ethics Committee, the authors
retrospectively assessed the medical record data of patients with spastic CP, classified
as
GMFCS IV and V, operated at this hospital from June 2013 to June 2015, submitted to
VDSO.
The osteotomy was performed alone or associated with other procedures as part of the
multilevel approach recommended for the orthopedic surgical treatment in CP, called
single-event multilevel surgery (SEMLS).18,19 The following data were
compiled and tabulated in Excel: age, gender, anatomic classification of CP (diparesis,
tetraparesis, hemiparesis), pattern of motor involvement (pyramidal/spastic or
extrapyramidal/non-spastic), type of implant used, functional classification (GMFCS),
concomitant surgeries, and peri and postoperative complications. The radiographic
criteria
evaluated included the cervicodiaphyseal angle (CDA), acetabular index (AI), Reimers
migration index (RMI), and time to radiographic bone consolidation.

Patients who could not be followed-up for a minimum period of 2 years postoperatively
were
excluded from the study, as well as those with extrapyramidal motor involvement, those
classified as GMFCS I, II or III, and those who did not present complete data in medical
records.

Radiographs were evaluated by three authors of the study, two fourth-year residents
in
pediatric orthopedics, and one senior pediatric orthopedist at this institution (Fig. 1). CDA, AI, and RMI were measured as broadly
described in the literature, in a panoramic anteroposterior hip radiograph. The internal
rotation of the lower limbs on this radiograph was enough to compensate the anteversion
of
the femoral neck, usually close to 40 degrees,20 as
estimated previously by the trochanteric prominence test in the prone physical
examination.21,22 The authors used the Kalen and Bleck classification to assess the
progression of the degree of migration, in which a change of less than 10% was considered
unaltered, an increase of more than 10% was considered as a worsening of the condition,
and
a reduction of more than 10%, an improvement.23

Radiographic exams were performed preoperatively, as well as in the immediate postoperative
period (IPO), one month, six months, and one year postoperatively, in the panoramic
anteroposterior and double abduction views of the hip. The osteotomy was considered
to be
consolidated when a bone callus that crossed the fracture focus in at least three
of four
cortices was observed in the two radiographic projections.

The surgical technique used for VDSO was that previously described by Rutz et al.,15 except for the fact that, in the present study, a
1.5-cm femoral shortening was made; the distal fragment was secured with various
configurations of cortical and locking screws, which will be the focus of discussion
in
subsequent studies, and will not be detailed here.

Postoperative bilateral long leg hip spica cast immobilization was used in patients
who
also underwent open hip reduction or acetabuloplasty. In cases in which the VDSO was
isolated, a double abduction boot cast immobilization was used, consisting of a bilateral
plaster cast with an abductor bar. The plaster cast was used for two weeks, at which
point
patients underwent their first postoperative outpatient assessment. If the patient
was
comfortable and had no skin lesions related to the cast, a follow-up appointment was
rescheduled for every other week; the plaster was removed at the surgeon's discretion,
according to the radiographic image of the initial bone callus. In the case of long
leg hip
spica cast, the patient was taken to the operation room after four weeks of surgery
and the
immobilization was replaced by a double abduction cast, whose removal followed the
described
previously protocol.

Postoperative complications were classified by the main author according to the adapted
Clavien-Dindo method,24 in which grade I
complications are those that do not require a change in standard treatment, grade
II require
a change in outpatient treatment, grade III require radiological or surgical intervention,
grade IV are associated with long-term morbidity or life-threatening, and grade V
result in
patient death.25

The normality of the quantitative data was assessed with the Kolmogorov-Smirnov test.
The
AI, CDA, and RMI values were compared using the Student's t-test for paired
samples. Unpaired samples were compared with Student's t-test for unpaired
samples. Qualitative data were compared using Fisher's exact test. The online Quickcalcs
version of the Graphpad software was used for these evaluations (Graphpad Software,
San
Diego, CA, USA). A significance level of 5% (α = 0.05) was
adopted.

RESULTS

Eighty patients with CP classified as GMFCS IV or V underwent surgery from June 2013
to
June 2015. Of these, 42 patients (61 hips) were included in the study group; the others
were
excluded due to the absence of standardized radiographs that allowed adequate measures
(18
cases) and the remainder because they did not complete the two years of outpatient
follow-up
(20 cases). The majority of patients were female (25 patients, 40 hips). The mean
age was
8.7 years (range: 4-14 years). All patients had spastic tetraparesis; 34 (46 hips)
were
classified as GMFCS V and eight (15 hips) as GMFCS IV (Table
1). An isolated VDSO was performed in 30 hips, while it was associated with
Dega-type supra-acetabular osteotomy in 31 hips. In these latter 31 hips, an arthrotomy
was
performed for open reduction of the joint in 17 cases (54.8%). Multiple tenotomies
were
performed in all patients; tenotomy of the intrapelvic psoas was performed in 17 hips
(27.8%), psoas tenotomy at the small trochanter in 44 (72.1%), long adductor tenotomy
in 51
hips (83.6%), gracilis tenotomy at its origin in 13 hips (21.3%), and distal lengthening
of
the medial hamstrings in 47 limbs (77%). In two patients, the flexor-pronator musculature
was lengthened. The implant used was the 110° 3.5-mm pediatric proximal femur LCP
(Synthes,
Oberdorfen, Switzerland) in 56 cases (90.3%), the 100° plate in five cases (8.06%)
and the
120° plate in one case (1.6%). The mean follow-up time was 41.36 months (from 26 to
59),
while the mean postoperative immobilization time was 5.5 weeks (from 3 to 12) and
the mean
time until consolidation was 12.75 weeks (from 6 to 52).

Table 1. Sample characterization.

GMFCS

Number of patients (hips)

Gender (male:female)

Mean age (years)

IV

8 (15)

6:2

7.6

V

34 (46)

11:23

9.8

Total

42 (61)

17:25

8.7

GMFCS, Gross Motor Function Classification System.

Table 1. Sample characterization.

The mean preoperative CDA was 154.6° and the mean postoperative was 119.6°, with an
average
reduction of 35.1°. Regarding the AI, the mean reduction was 6.03°, with pre and
postoperative means of 21.09° and 15.06°, respectively. Finally, the RMI presented
a mean
reduction of 66.5% between the pre and the immediate postoperative period (IPO), while
the
reduction in the late postoperative period (LPO) was 58.92%, i.e., there was a loss
of 7.58%
in the late postoperative follow-up, in relation to the preoperative period. A significant
difference was observed between pre and postoperative CDA and AI (p <
0.0001), as well as between pre and postoperative RMI (p < 0.0001; Table 2). The worsened RMI observed in the LPO in
relation to the IPO was considered unaltered according to the classification of Kalen
and
Bleck. Meanwhile, in all cases, an improvement in migration was observed after surgery,
according to the same classification.23 The monthly
rate of postoperative progression of the RMI, which was on average 0.31%/month, was
calculated by dividing the difference between the RMI at the LPO and that observed
at the
IPO by the time of follow-up.

Postoperative complications were observed in 14 patients (33.3% of the patients, or
29.5%
of the hips), a second surgical procedure was necessary for six patients (14.3%).
All
complications were observed in GMFCS V patients. Of these complications, six were
classified
as type II of Clavien-Dindo, in which only therapeutic treatment was necessary for
an
outpatient setting, with six pressure ulcers (five in the sacral region and one in
the
calcaneus). Six patients had complications classified as type III that required a
supplementary orthopedic approach; five cases of re-dislocation and one case of
pseudoarthrosis. Two patients presented clinical complications and required treatment
under
hospital admission; they were classified as type IV (one case of intestinal obstruction
due
to adhesions and one case of pneumonia requiring parenteral antibiotic therapy).

A higher mean CDA was observed in the group with complications (154.7°) when compared
with
the uncomplicated group (121.6°), a statistically significant difference (p
< 0.0001). The difference between the mean AI of complicated (20.48°) and uncomplicated
(22.71°) cases was not statistically significant (p = 0.201). Finally, mean
RMI was statistically lower in uncomplicated cases (65.44%) than in complicated cases
(81.17%; p = 0.0054). This indicates an association between greater CDA and
greater RMI with a higher rate of complications, whereas the same was not observed
with AI
(Fig. 2).

No statistical significance was observed when assessing the relationship between
complications, side, and age. However, in the GMFCS functional classification, a significant
association was observed with class V in relation to IV (p < 0.0001). No
statistically significant association was observed regarding the complications and
the
surgeries associated to the VDSO.

DISCUSSION

The prevalence of paralytic hip dislocation in patients with spastic CP is directly
proportional to the degree of functional impairment (GMFCS), reaching up to 70% and
90% in
grades IV and V, respectively.1,4-7
Failure to identify this dislocation early in the follow-up of patients with spastic
CP may
lead to significant pain and severe limitation of patients' quality of life.1,26,27 This fact led to the
creation of early prevention and diagnosis programs through an intermittent programmed
follow-up of GMFCS IV and V patients in several orthopedic centers worldwide, which
allowed
a preventive surgical approach and a consequent lower rate of dislocations with secondary
joint degeneration.4,7 In the state of Rio de Janeiro, Brazil, the logistics for the
implementation of a similar public health program are hampered by the low number of
patients
undergoing adequate physical therapy, as well as the high cost of botulinum toxin,
commonly
used to delay the age at which patients undergo surgical procedures. The difficulty
of using
this toxin in the iliopsoas musculature, fundamental in the deformity in question,
is also a
limiting factor. Together, these factors are linked to the dislocation and subluxation;
however, the literature does not present definitive evidence.26

Cooke et al.28 retrospectively studied 462 patients
to identify factors associated with the paralytic hip dislocation in CP patients,
and
determined an association of this with a higher AI; these authors indicated that AI
> 30°
before 4 years of age is an important predictor. In the present sample, no relationship
was
observed between AI and the incidence of complications in the treatment of hip dislocation.
However, the present authors were unable to perform an assessment similar to that
of Cooke
et al., as the entire sample in the present study consisted of patients who already
presented dislocation or subluxation, which would cause a selection bias if a parallel
were
to be drawn. In addition, the definition of AI as a predictor can be questioned, as
it is
known that the femoral head positioned in the hip helps to shape the acetabulum, which
is
well documented in hip development in cases of dysplasia29,30; the AI alteration could,
therefore, be seen as a consequence, not a cause of the dislocation.

In 2006, a Norwegian group10 evaluated the natural
history of non-operated hips in 76 patients with CP and found a relationship between
paralytic dislocation and two factors: no independent ambulation for up to five years
of age
and degree of motor involvement, with a higher RMI progression in tetraparesis in
relation
to diparesis. These data were confirmed in a subsequent study by the same group in
2012.7 A progression of RMI at one year of 7.58% was
observed in the present study, with a rate of 0.31%/month, which is lower than that
described in the literature, which is around 12% a year in untreated cases.7,10
Therefore, this intervention slows down but does not completely prevent RMI progression.
There is no evidence that postoperative non-surgical measures, such as physical therapy,
can
alter this parameter. Thus, the challenge is to define the best time to perform the
VDSO in
order to require as few subsequent surgical interventions as possible. At the same
time,
this challenge becomes greater when trying to determine the moment at which the femoral
head
is positioned in the hip and leads to acetabulum remodeling, which may not necessarily
be at
the same moment that it decreases the chance of the patient requiring new hip surgeries.

Other authors correlated RMI with the chance of re-dislocation, which was consistent
with
the present results.31 This association could be
attributed to local adaptive factors, such as greater soft-tissue retraction in cases
where
there is greater lateral hip migration. It can also be hypothesized that this finding
is
related to the severity of the patient's functional impairment and spasticity, as
patients
with GMFCS IV and V tend to have higher RMI and a greater incidence of hip dislocation.4,12,31

The consolidation time was comparable to that described in the literature, as well
as the
preoperative CDA and RMI measurements and their postoperative improvement,15-17
even with the use of several implants (locking blade plate or non-locking blade plate
in
these studies). The rate of complications in the literature after reconstructive surgeries
of the paralytic hip was in the range of 26%, vs. 29.5% in the present sample. However,
the
present rate of orthopedic complications was 6/61, or 9.83%, which was lower than
reported
in a New Zealand study,17 but somewhat higher than
another study conducted in Switzerland (5.7%).15 A
more recent Australian study assessed the results of the use of a locking blade plate
in a
group with a short follow-up and did not observe cases of failure in the surgical
treatment
in the period until consolidation. Since all the complications in the present study
that
required a new surgical approach occurred prior to osteotomy consolidation, the authors
infer that this technique requires a learning curve still in progress in the present
service
to reach lower complication rates equivalent to that of reference services, which
perform
over 150 osteotomies per year.16

The present study had limitations, such as the absence of a control group, composed
of
GMFCS IV and V patients who underwent reconstructive surgeries of the hip with non-locking
plates. This control group is currently under follow-up, and this comparative study
is the
current focus at the present institution. Nonetheless, the number of operated patients
is a
considerable and unprecedented sample in the Brazilian literature. The inclusion of
intraoperative measures of bleeding, as well as the assessment of hospital cost for
both
techniques, and hospitalization and complications, it is important to evaluate the
feasibility of using these locking implants in the public healthcare system. These
data are
under evaluation and the authors intend to publish a specific study on the issue.

CONCLUSION

In the present sample, paralytic hip reconstruction surgery performed with a 3.5-mm
pediatric LCP hip plate was shown to be a safe, reproducible technique with a low
rate of
surgical complications, that reduces the speed of hip lateral migration in non-ambulatory
CP
patients. Higher preoperative CDA and RMI were associated with higher rates of postoperative
complications, as well as GMFCS V classification.

Hagglund G, Alriksson-Schmidt A, Rodby-Bousquet E, Wagner P, Westbom L.
Prevention of dislocation of the hip in children with cerebral palsy: 20 year results
of a
population based prevention programme. Bone Joint J. 2014;96(11):1546-52.